Ecotoxicological effects of rare earth elements on early life stages of fish

Rare earth elements, comprising the 15 lanthanoids (LN; IIIb in the Periodic Table) plus yttrium are critical elements for a wide range of applications, including new and traditional industries as renewable energy, automotive industries, metallurgy as well as agriculture and medical diagnostics. Rising REY production and use can lead to an increased release into the environment and represents a potential environmental concern. However, the bioavailability and effects of REY and anthropogenic REY-chemical complexes (ACC-REY) remain significantly understudied in aquatic organisms.Here, we evaluated the impact of different REY and ACC-REY on early life stages of two fish species: zebrafish (Danio rerio) as freshwater model species and cod (Gadus morhua) as marine species. Fish embryos were exposed to nominally 2000, 200, 20, 2 and 0.2 µg L-1 of different REY compounds. Mortality, hatching, larvae development and morphometry were monitored. At the end of the exposure, a subsample of larvae from each treatment was subjected to image analyses to evaluate larvae mobility and behaviour. These individuals were thereafter analysed immunohistochemically to investigate REY impacts on neural activity. First results showed increased mortality and larvae deformation at higher REY concentrations. Further, transcriptomic responses are analysed to reveal underlying molecular effect mechanisms and affected pathways. Results from this study will provide knowledge on the eco-toxicological risks associated to increasing REY release into aquatic ecosystems.